From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-13.6 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 49444C433DB for ; Sat, 20 Mar 2021 20:09:45 +0000 (UTC) Received: from gabe.freedesktop.org (gabe.freedesktop.org [131.252.210.177]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id A93B261939 for ; Sat, 20 Mar 2021 20:09:44 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org A93B261939 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=ideasonboard.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=dri-devel-bounces@lists.freedesktop.org Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id 225D76E0D0; Sat, 20 Mar 2021 20:09:44 +0000 (UTC) Received: from perceval.ideasonboard.com (perceval.ideasonboard.com [IPv6:2001:4b98:dc2:55:216:3eff:fef7:d647]) by gabe.freedesktop.org (Postfix) with ESMTPS id 7DD856E0D0 for ; Sat, 20 Mar 2021 20:09:42 +0000 (UTC) Received: from pendragon.ideasonboard.com (62-78-145-57.bb.dnainternet.fi [62.78.145.57]) by perceval.ideasonboard.com (Postfix) with ESMTPSA id DB6908D3; Sat, 20 Mar 2021 21:09:39 +0100 (CET) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=ideasonboard.com; s=mail; t=1616270980; bh=54YnA6l0786MMgUPy84Ruh3n0/JWV766Jm/XCuHtZkM=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=Eail8CqSdt10yknT3xISYwD++Hce7WTsNdJeFK6jv0EG5UdaNab56PMyp7aubFBSN Sa75AooJS4DIWWkk9l2OfIz05s6qcoRhxsIOjYJ0kvF7BIH5NKKvsqR2roKdHz4ZTK oBWbsRUmtbKfBTBwSonoD70beeIHxiLj1rYLpktg= Date: Sat, 20 Mar 2021 22:08:59 +0200 From: Laurent Pinchart To: quanyang.wang@windriver.com Subject: Re: [PATCH] drm: xlnx: zynqmp: release reset to DP controller before accessing DP registers Message-ID: References: <20210320083739.724246-1-quanyang.wang@windriver.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20210320083739.724246-1-quanyang.wang@windriver.com> X-BeenThere: dri-devel@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Direct Rendering Infrastructure - Development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Hyun Kwon , David Airlie , Michal Simek , dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" Hi Quanyang, Thank you for the patch. On Sat, Mar 20, 2021 at 04:37:39PM +0800, quanyang.wang@windriver.com wrote: > From: Quanyang Wang > > When insmod zynqmp-dpsub.ko after rmmod it, system will hang with the > error log as below: > > root@xilinx-zynqmp:~# insmod zynqmp-dpsub.ko > [ 88.391289] [drm] Initialized zynqmp-dpsub 1.0.0 20130509 for fd4a0000.display on minor 0 > [ 88.529906] Console: switching to colour frame buffer device 128x48 > [ 88.549402] zynqmp-dpsub fd4a0000.display: [drm] fb0: zynqmp-dpsubdrm frame buffer device > [ 88.571624] zynqmp-dpsub fd4a0000.display: ZynqMP DisplayPort Subsystem driver probed > root@xilinx-zynqmp:~# rmmod zynqmp_dpsub > [ 94.023404] Console: switching to colour dummy device 80x25 > root@xilinx-zynqmp:~# insmod zynqmp-dpsub.ko > > > This is because that in zynqmp_dp_probe it tries to access some DP > registers while the DP controller is still in the reset state. When > running "rmmod zynqmp_dpsub", zynqmp_dp_reset(dp, true) in > zynqmp_dp_phy_exit is called to force the DP controller into the reset > state. Then insmod will call zynqmp_dp_probe to write to the DP registers, > but at this moment the DP controller isn't brought out of the reset state > since the function zynqmp_dp_reset(dp, false) is called later and this > will result the system hang. > > Releasing the reset to DP controller before any read/write operation to it > will fix this issue. > > Signed-off-by: Quanyang Wang > --- > drivers/gpu/drm/xlnx/zynqmp_dp.c | 8 ++++---- > 1 file changed, 4 insertions(+), 4 deletions(-) > > diff --git a/drivers/gpu/drm/xlnx/zynqmp_dp.c b/drivers/gpu/drm/xlnx/zynqmp_dp.c > index 99158ee67d02..bb45b3663d6b 100644 > --- a/drivers/gpu/drm/xlnx/zynqmp_dp.c > +++ b/drivers/gpu/drm/xlnx/zynqmp_dp.c > @@ -402,10 +402,6 @@ static int zynqmp_dp_phy_init(struct zynqmp_dp *dp) > } > } > > - ret = zynqmp_dp_reset(dp, false); > - if (ret < 0) > - return ret; > - > zynqmp_dp_clr(dp, ZYNQMP_DP_PHY_RESET, ZYNQMP_DP_PHY_RESET_ALL_RESET); > > /* > @@ -1682,6 +1678,10 @@ int zynqmp_dp_probe(struct zynqmp_dpsub *dpsub, struct drm_device *drm) > return PTR_ERR(dp->reset); > } > > + ret = zynqmp_dp_reset(dp, false); > + if (ret < 0) > + return ret; > + This change looks good to me. > ret = zynqmp_dp_phy_probe(dp); > if (ret) > return ret; But shouldn't we call zynqmp_dp_reset(dp, true) here ? Or rather, call it in the error path at the end of the function, with a goto label. For symmetry, should we also move the zynqmp_dp_reset() call from zynqmp_dp_phy_exit() to zynqmp_dp_remove() ? -- Regards, Laurent Pinchart _______________________________________________ dri-devel mailing list dri-devel@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/dri-devel